Orthogonal frequency-division multiplexing (OFDM) waveforms have been used successfully in various communication systems including terrestrial only systems, hybrid terrestrial/satellite systems, and satellite only systems. OFDM signals typically include a guard interval to reduce the effects of multipath interference, in particular inter-symbol interference (ISI) caused by temporally distinct symbols arriving at a receiver at the same time. A commonly used guard interval is the so-called cyclic prefix (CP) guard interval. The guard intervals of CP-OFDM signals repeat or replicate a portion of the symbol-data being transmitted. However, since the energy or information in the CP guard interval is typically discarded by a receiver as it is presumed to be affected by ISI, a CP-OFDM based system suffers from a signal energy efficiency loss. For example, if a CP-OFDM signal employs a one-quarter (¼) guard interval, the transmitted signal includes 25% of the usable data replicated and added to the original usable data. This means that the time to transmit the usable data takes 125% of the time actually needed, and only 100/125 or 80% of the transmitted signal energy is used to decode data from the received signal.